The present invention is directed to a drilling and/or chiseling tool formed basically by shaping without cutting and includes an axially extending shaft having a leading end and a trailing end in the drilling direction. A shank is located at the trailing end and a drilling head with one or more hard metal inserts is located at the leading end. The shaft has helical drilled material removal grooves extending from the drilling head towards the shank with the hard metal inserts being secured in a recess at the leading end of the drilling end.
Tools of the above-mentioned type are used for working in rock, concrete, masonry and similar hard materials. At the trailing end of such tools, shanks are arranged for engagement in driving or drilling devices. A shaft with helical drilled material removal grooves extends axially from the shank in the drilling direction. A drilling head, with a recess open in the drilling direction is arranged for receiving one or more hard metal inserts. Since the hard metal inserts are arranged in a recess of the drilling head, they are supported on their sides by the drilling head. This has an advantageous effect on the connection between the hard metal inserts and the drilling head. Moreover, the hard metal inserts are supported over a large area by regions of the drilling head. This factor affords the strength to resist harmful effects arising out of the torque and the impacts applied at the drilling head.
The drilled material removal grooves in the shaft serve for carrying the drilled material or drillings developed as the tool is worked. To insure that the drillings are transported without interference from the drilling head into the removal grooves extending opposite to the drilling direction, an appropriate transition region must be provided in the drilling head. This transition region is present in the running out or end region of the removal grooves in the drilling direction. To assure that the hard metal inserts are still adequately supported by the drilling head in spite of the running out of the removal grooves, it must be insured that the running out of the grooves extends parallel to the shaft axis in the leading end region of the tool.
Due to the helical arrangement of the removal grooves, there is a relatively large deviation from the course of the running out sections parallel to the axis for conventional tools with one or two removal grooves. When such removal grooves extend into the drilling head without a sufficient correction regarding their slope, there may be inadequate support for the hard metal inserts. Accordingly, the tools presently in use employ a special design in the region of the drilling head where the removal grooves are arranged extending essentially parallel to the axis of the tool.
The above-mentioned necessary correction of the removal grooves leads to additional manufacturing expense resulting in a negative economical effect on the manufacturing procedure. As an example, if the removal grooves are formed by machine, a special control of the machine tools is required leading to an additional expenditure for equipment as well as an additional expenditure of time.
In place of machining, non-cutting procedures, such as shaping without cutting, is used at the present time for economic reasons. It is important that the bulk of the processing takes place by shaping without cutting and that certain steps in the procedure, such as the production of recesses for the hard metal inserts or a possible slight correction of the removal grooves, for example, in the running out region, can be effected by machine. For such economically significant shaping without cutting, the formation of the running out of the removal grooves at the drilling end of the tool essentially parallel to the tool axis also involves additional expense. Accordingly, a special additional rolling procedure is required for shaping the discharging grooves without any cutting, for example, by rolling, and this results in additional expense for equipment and an additional expenditure of time.
To avoid such additional expenditures where tools are formed by shaping without cutting, it has been known to weld the drilling head, consisting completely of hard metal, onto the shaft provided with removal grooves, instead of using hard metal inserts in appropriate recesses. Since such drilling heads, formed of hard metal, do not require any lateral support, separate processing of the drilling end of the shaft can be omitted.